JP2002246698A - Nitride semiconductor light-emitting device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light-emitting life and light-emitting intensity of a nitride semiconductor light-emitting device and to prevent the occurrence of a crack. SOLUTION: The nitride semiconductor light-emitting device comprises a processing substrate 101 which includes concave parts and convex parts formed on a surface of a nitride semiconductor layer grown on a substrate surface of a nitride semiconductor or on a substrate other than the nitride semiconductor, a nitride semiconductor base layer 102 grown on the uneven surface of the processing substrate, and a light-emitting device structure which includes a light-emitting layer 106 having a quantum well layer or the quantum well layer and a barrier layer between n-type layers 103 to 105 and p-type layers 107 to 110 on the base layer of the nitride semiconductor. Even after the base layer and the light-emitting device structure are grown, depressions not being flattened remain at least on the concave parts or the convex parts of the processing substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device having a long light emission life and reduced occurrence of cracks, and to an improvement in a method for manufacturing the same.

[0002]

2. Description of the Related Art In order to improve the light emitting characteristics of a nitride semiconductor light emitting device, a groove is formed in a GaN layer laminated on a sapphire substrate, and the groove is again flatly covered with a GaN film.
Forming a semiconductor laser device on the coating layer is reported in JP-A-2000-124500.

Japanese Patent Application Laid-Open No. 9-36473 reports that a semiconductor laser element is formed on a window region of a stripe-shaped SiO ₂ mask by using a selective crystal growth technique.

[0004]

SUMMARY OF THE INVENTION Even in the nitride semiconductor light emitting device manufactured by the above prior art,
There is a problem that the emission life is not sufficient.
Accordingly, it is a main object of the present invention to provide a nitride semiconductor light emitting device having a long light emission life and to suppress the occurrence of cracks in the device.

[0005]

In a nitride semiconductor light emitting device according to the present invention, a concave portion and a convex portion are formed on a surface of a nitride semiconductor substrate or on a surface of a nitride semiconductor layer grown on a substrate other than the nitride semiconductor. A nitride semiconductor underlayer grown on the uneven surface of the processed substrate; a quantum well layer or a quantum well layer between the n-type layer and the p-type layer on the underlayer; A light-emitting element structure including a light-emitting layer including a barrier layer in contact with the substrate, and even after growing the nitride semiconductor underlayer and the light-emitting element structure, flattening is performed above at least one of the concave portion and the convex portion of the processing substrate. It is characterized by including a notch. It is preferable that the processed substrate be entirely made of a nitride semiconductor.

Preferably, the concave portion of the processed substrate is a stripe-shaped groove, and the convex portion is a stripe-shaped hill. The uneven surface of the processed substrate is made of a nitride semiconductor, and the longitudinal direction of the groove and the longitudinal direction of the hill are <1-1 of the nitride semiconductor crystal.
Preferably, it is substantially parallel to the <00> or <11-20> direction.

There is no depression above the center of the width of the groove, and the light emitting portion of the light emitting element structure is included above the region at least 1 μm in the width direction from the center of the groove width and within the width of the groove. Is preferred. In this case, the groove width is preferably in the range of 4 to 30 μm. Preferably, the depth of the groove is in the range of 1 to 9 μm.

There is no depression above the center of the width of the hill, and a substantial light emitting region of the multilayer light emitting structure is formed above the region within the width of the hill at least 1 μm in the width direction from the center of the hill width. You may. In this case, the hill width is preferably in the range of 4 to 30 μm.

A recess is formed above the groove, and a substantial light emitting region of the multilayer light emitting layer is formed above a region separated from the side end of the recess by at least 2 μm in the width direction of the groove and within the width of the groove. It may be. In this case, the groove width is 7 to 100 μm
Is preferably within the range. The groove depth is 1μ
m or more, and the remaining thickness between the bottom of the groove and the back surface of the substrate is preferably 100 μm or more.

A recess is formed above the hill, and a substantial light emitting region of the multilayer light emitting structure is formed above a region which is at least 2 μm in the width direction of the hill from a side end of the recess and is within the width of the hill. It may be. In this case, the hill width is 7-100μ
It is preferably within the range of m.

The nitride semiconductor underlayer is GaN, and S
It contains at least one or more of i, O, Cl, S, C, Ge, Zn, Cd, Mg and Be impurity groups, and has an addition amount of 1 × 10 ¹⁷ / cm ³ or more and 5 × 10 ¹⁸ /
cm ³ or less.

The nitride semiconductor underlayer is Al _x Ga ₁ -xN
(0.01 ≦ x ≦ 0.15), and Si,
O, Cl, S, C, Ge, Zn, Cd, Mg and Be
It is preferable that at least one of the impurity groups described above is contained, and the added amount is 3 × 10 ¹⁷ / cm ³ or more and 5 × 10 ¹⁸ / cm ³ or less.

The nitride semiconductor underlayer is made of In _x Ga ₁ -xN.
(0.01 ≦ x ≦ 0.15), and Si,
O, Cl, S, C, Ge, Zn, Cd, Mg and Be
It is preferable that at least one of the impurity groups described above is contained, and the added amount is 1 × 10 ¹⁷ / cm ³ or more and 4 × 10 ¹⁸ / cm ³ or less.

Preferably, the electrode is formed on a region including two or more depressions. Similarly, it is preferable that a dielectric film is formed on a region including two or more depressions. The bonding region between the wire bond and the nitride semiconductor light emitting device preferably includes one or more depressions.

The quantum well layer preferably contains at least one of As, P, and Sb.

[0016] The nitride semiconductor light emitting device can be either a laser device or a light emitting diode device. Such a nitride semiconductor light emitting element can be a component of various optical devices or semiconductor light emitting devices.

On the other hand, in the method for manufacturing a nitride semiconductor light emitting device according to the present invention, the concave and convex portions formed on the surface of the nitride semiconductor substrate or on the surface of the nitride semiconductor layer grown on a substrate other than the nitride semiconductor are formed. A processed substrate including the above is prepared, a nitride semiconductor underlayer is grown on the uneven surface of the processed substrate, and a quantum well layer or a quantum well layer is formed between the n-type layer and the p-type layer on the nitride semiconductor underlayer. And a step of growing a light-emitting element structure including a light-emitting layer including a barrier layer in contact therewith, and after growing the underlayer and the light-emitting element structure, at least one of the concave portion and the convex portion of the processing substrate. It is characterized in that a non-planarized depression is formed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, in describing various embodiments of the present invention, the meaning of some terms will be clarified in advance.

First, the "groove" means a concave portion processed in the form of a stripe on the surface of the processed substrate as shown in FIGS. 2A and 2B, for example. Means a convex part processed into a shape. The cross-sectional shapes of the grooves and hills do not necessarily have to be rectangular as shown in FIG. 2, but may be any as long as they cause unevenness.
Further, the grooves and hills shown in FIG. 2 have a stripe arrangement processed along one direction, but may have a mesh arrangement in which the grooves or hills cross each other (see FIG. 5). In the drawings of the present application, dimensional relationships such as length, width, thickness, and depth are appropriately changed for clarification and simplification of the drawings, and do not represent actual dimensional relationships.

[0020] The term "nitride semiconductor substrate", Al _x Ga _y I
_nz N (0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z ≦ 1; x + y
+ Z = 1). However, about 10% or less of the nitrogen element of the nitride semiconductor substrate is A
It may be replaced by an element of s, P, or Sb (provided that the hexagonal system of the substrate is maintained). Also,
Si, O, Cl, S, C, G in a nitride semiconductor substrate
e, Zn, Cd, Mg, or Be may be doped. Among these doping materials, Si, O, and Cl are particularly preferable as the n-type nitride semiconductor. The principal plane orientation of the nitride semiconductor substrate is as follows.
01｝, A plane {11-20}, R plane {1-102}, M
The plane {1-100} or {1-101} plane can be preferably used. In addition, if the main surface of the substrate has an off angle within 2 ° from these crystal plane directions, the surface morphology may be good.

The "heterogeneous substrate" means a substrate other than a nitride semiconductor. As a specific heterogeneous substrate, a sapphire substrate, a SiC substrate, a Si substrate, a GaAs substrate, or the like can be used.

The term "processed substrate" means a substrate having grooves and hills formed on the surface of a nitride semiconductor substrate or on the surface of a nitride semiconductor layer grown on a heterogeneous substrate. The width of the groove and the width of the hill may have a fixed period, or may have various widths. Also, regarding the depth of the groove,
All grooves may have a constant depth or may have various different depths.

[0023] The "nitride semiconductor underlayer", is a layer that is grown on the uneven surface of the processed substrate, Al _x Ga _y In
_z N (0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z ≦ 1; x + y +
z = 1). However, Si, O, Cl, S, C, Ge, Zn, C
at least one of an impurity group of d, Mg, and Be
The species may be doped.

The term “light emitting layer” means a layer capable of producing a light emitting action, including one or more quantum well layers or a plurality of barrier layers alternately stacked thereon. However, the light emitting layer having a single quantum well structure is composed of only one well layer or a laminate of barrier layers / well layers / barrier layers.

The “light emitting element structure” means a structure further including an n-type layer and a p-type layer sandwiching the light emitting layer in addition to the light emitting layer.

The term "nitride semiconductor multilayer film structure" means a structure including a nitride semiconductor underlayer and a light emitting device structure.

The “dent” means that when a nitride semiconductor underlayer or a nitride semiconductor multilayer film structure is grown and covered on an uneven surface of a processed substrate, the nitride semiconductor underlayer or the nitride semiconductor multilayer film structure is removed. It means a portion that is not buried flat (see FIG. 3 for an example in which the depression is on the surface of the nitride semiconductor underlayer). In particular, the depression in the present invention must always exist on the surface of the nitride semiconductor multilayer structure. However, the effect of the invention of the present application cannot be obtained even if a depression is formed by etching or the like after the nitride semiconductor multilayer film structure is flatly covered on the processed substrate. Whether or not the depression is formed by processing after the crystal growth becomes clear by observing the cross section of the nitride semiconductor multilayer film structure. The reason is that if a pit is formed by processing after completion of crystal growth, the continuity in the lateral direction in the stack in the light emitting element structure is cut off by the pit, but if the pit is formed along with the crystal growth, the light emitting element This is because the continuity in the lateral direction in the stack in the structure is not cut off by the depression, but continues along the side wall surface of the depression.

The term “substrate with depression” means an entire substrate including a depression on which a nitride semiconductor base layer is coated on a processing substrate (see FIG. 3).

The term “coating film thickness” means the film thickness from the bottom of the groove to the surface of the nitride semiconductor layer excluding the depression when the nitride semiconductor layer is grown on the processed substrate. .

[Embodiment 1] As a result of the study by the present inventors,
It is considered that the effect of extending the life of the nitride semiconductor light emitting device obtained by the present invention may be due to relaxation of strain in the nitride semiconductor multilayer film structure crystal included in the device. FIG. 2 shows the form of the processed substrate used in the present invention and the name of each part, FIG. 4A shows the form of crystal growth in the present invention, and FIG. FIG. 4C shows a form of crystal growth in which a multilayer film structure is completely and flatly covered, and FIG. 4C shows a form of crystal growth by a conventional selective crystal growth method using a crystal growth suppressing film. When the present inventors arrived at the present invention, they first examined a conventional crystal growth mode.

(Conventional Crystal Growth Form) In FIG. 4B, for example, as taught in Japanese Patent Application Laid-Open No. 2000-124500, when a processed substrate is completely and flatly covered with a nitride semiconductor multilayer film structure. Then, crystal growth starts in the horizontal direction (hereinafter referred to as lateral growth) from the side wall of the groove formed in the processed substrate. When such lateral growth occurs, a crystal reflecting the crystal lattice of the lower substrate is difficult to grow, and crystal distortion from below is relaxed. However, the crystals grown from the groove side walls on both sides collide with each other at the center of the groove shown in FIG.
The crystals that collide in the center of the groove will then grow in the normal crystal growth direction (perpendicular to the main surface of the substrate), and will bury the uncovered hills completely and flatly. From the center to the center of the hill, the opposite lateral growth is promoted. The same collision of crystals as in the center of the groove described above also occurs in the center of the hill, and as a result, the concentration of crystal strain due to the collision of crystals also occurs in the center of the hill. Then, while the center of the hill is buried, or when the center of the hill is completely buried, the crystal growth proceeds in a normal crystal growth direction.

Therefore, in the conventional crystal growth mode shown in FIG. 4B, if the processed substrate is completely covered with the nitride semiconductor multilayer structure, the crystal strain is concentrated at the center of the groove and the center of the hill. Resulting in. Moreover, even in regions other than the center of the groove and the center of the hill, even if the crystal growth from below is relaxed by the lateral growth, residual strain occurs due to the concentration of crystal strain at the center of the groove and the center of the hill. I will. It is considered that the light emitting life of the semiconductor light emitting device is shortened due to the above crystal distortion.

On the other hand, in FIG. 4C, as taught in, for example, Japanese Patent Application Laid-Open No. 9-36473, selective crystal growth (corresponding to lateral growth) using a growth suppressing film such as an SiO ₂ mask, for example. ), It is possible to form a dent not completely covered with the nitride semiconductor film on the growth suppressing film, similar to the crystal growth mode of the present invention (see FIG. 4A). However, the selective crystal growth using the growth suppressing film is different from the crystal growth mode using the processed substrate in the present invention described below. This is because, when the growth suppressing film is used, as shown in FIG. 4C, the crystal growth of the nitride semiconductor film starts from the window region of the GaN layer not covered with the growth suppressing film. The nitride semiconductor film growing in this window region grows in a normal crystal growth direction (a direction perpendicular to the main surface of the substrate). Therefore, the crystal grown above the window region (the hatched portion in FIG. 4C) is a crystal strain (including a strain due to a difference in thermal expansion coefficient) from the GaN layer and the sapphire substrate below.
Receive. As a result of detailed studies by the present inventors,
The portion where the crystal strain was relaxed was only the region above the crystal growth suppressing film shown in FIG.

However, even when a nitride semiconductor light emitting device was manufactured in the region above the crystal growth suppressing film, the light emitting life was shorter than that of a light emitting device according to the present invention described later. This is probably due to the fact that the nitride semiconductor film and the growth suppressing film were distorted due to the difference in thermal expansion coefficient and the impurities contained in the growth suppressing film were doped into the light emitting device structure through the recessed portions. .

For example, if the growth suppressing film expands or contracts in volume due to a change in temperature, a difference in thermal expansion coefficient causes a distortion in a direction perpendicular to the main surface of the substrate and a distortion in a portion where the crystal in the region above the window and the growth suppressing film contacts the window. It is considered that it propagates to the region above the growth suppressing film. In addition, the volume expansion or contraction of the growth suppression film causes the region above the growth suppression film to be raised,
A gap may be generated between the region above the growth suppressing film and the growth suppressing film, and the region above the growth suppressing film may be curved. Such a phenomenon not only gives a crystal strain to the region above the growth suppressing film but also lowers the crystal orientation. Furthermore, when the growth suppressing film is SiO ₂ , it is considered that the Si or O is excessively doped into the light emitting element structure via the depression. It is considered that these factors overlap and the laser emission life was short even when a semiconductor light emitting device was manufactured in the region above the growth suppressing film.

(Crystal Growth Form in the Present Invention) FIG.
In the crystal growth mode according to the present invention shown in FIG. 4A, as in the conventional example shown in FIG. 4B, the lateral growth starts from the side wall of the groove formed in the processing substrate, and the both sides grow. The crystals grown from the groove side walls meet at the center of the groove in FIG. 4A, and thereafter the growth proceeds in the normal crystal growth direction. However, in the crystal growth mode according to the present invention, since the nitride semiconductor multilayer film structure has a dent above the hill that is not completely buried, horizontal crystal distortion parallel to the main surface of the substrate is caused through the dent. Can be relaxed. That is, the depression can reduce the crystal strain concentrated at the center of the groove in the conventional crystal growth mode shown in FIG. 4B, and can reduce the crystal strain of the entire nitride semiconductor multilayer structure. Further, in the crystal growth mode according to the present invention, since the growth suppressing film shown in FIG. 4C is not used, the crystal growth film is affected by the above-mentioned difference in thermal expansion coefficient and impurity doping. Absent.

In the crystal growth mode of the present invention, it is more preferable that the depression is formed not only at the center of the hill but also at the center of the groove (see Embodiment 3). By utilizing such a crystal growth mode, there is no portion where crystal strain is concentrated, so that it is possible to form a nitride semiconductor multilayer film structure in which crystal strain is almost alleviated.

(Effects of the present invention) As described above, in the present invention, when a nitride semiconductor multilayer film structure is formed on a processing substrate, the nitride Crystal distortion of the semiconductor multilayer structure can be reduced.

When a nitride semiconductor laser device is formed on a processing substrate according to the present invention using the nitride semiconductor substrate (for example, a GaN substrate) shown in FIG. 2A, a laser output of 30 mW and an ambient temperature of 60 ° C. Under these conditions, the oscillation lifetime of the nitride semiconductor laser device was about 18,000 hours. This is much longer than the laser oscillation life of about 700 hours when a conventional nitride semiconductor substrate is used.

On the other hand, when a nitride semiconductor laser device is manufactured on a processing substrate according to the present invention using a heterogeneous substrate (for example, a sapphire substrate) shown in FIG. 2B, a laser output of 30 mW and an ambient temperature of 60 ° C. Under the conditions, the oscillation life of the nitride semiconductor laser device was about 1000 hours. This is sufficiently longer than the conventional laser oscillation life of about 200 hours when a different kind of substrate is used.

The present inventors have also found that the use of the processed substrate according to the present invention can suppress the occurrence of cracks in the light emitting device. As a result, the yield was improved in the productivity of the light emitting device.

For example, when a nitride semiconductor laser device is formed on a processed substrate according to the present invention using the nitride semiconductor substrate (GaN substrate) shown in FIG. cm ² . On the other hand, the conventional G
When a light emitting device structure made of a nitride semiconductor was formed on an aN substrate, it was thought that almost no cracks occurred. However, many cracks were found in the epiwafer surface after the light emitting device structure was actually grown. Had occurred. This is considered to be due to distortion due to the light emitting element structure being composed of a laminated structure of various layers (for example, AlG
The aN layer has a smaller lattice constant than the GaN layer,
The N layer has a larger lattice constant than the GaN layer.) Further, it is considered that the GaN substrate obtained by the current technology has a residual strain in the substrate itself. In fact, when a nitride semiconductor laser device was formed on a conventional GaN substrate, the crack density was about 5 to 8 lines / cm ² . From this, it was found that the crack density can be reduced by using the processed substrate of the nitride semiconductor in the present invention.

On the other hand, when the nitride semiconductor laser device is formed on the processed substrate in the present invention using the heterogeneous substrate shown in FIG. 2B, the crack density is about 3 to 5 lines / cm.
^{Was 2} . On the other hand, when a nitride semiconductor laser device is manufactured on a conventional processed substrate using a heterogeneous substrate,
The crack density was about 10 to 20 cracks / cm ² . From this, even in the case of a processed substrate including a heterogeneous substrate,
It has been found that the crack density can be reduced by using the processed substrate in the present invention.

The effect of suppressing cracks due to the above-mentioned depressions is as follows.
The strength was stronger as the depth of the depression was deeper, and stronger as the density of the depression was higher. In order to make the depression deeper, it is effective to make the groove deeper, widen the groove, or widen the hill when forming the processing substrate. On the other hand, in order to increase the density of the depressions, it is effective to reduce the groove width or the hill width when forming the processing substrate. Specific numerical values such as the groove width, the groove depth, and the hill width will be described later in more detail.

Further, it was found that the effect of suppressing depression cracks in the present invention has the following characteristics. In one nitride semiconductor light emitting device divided into chips, two dents are formed.
By including more than one element, the crack generation rate was reduced by about 30% as compared with one element.
Moreover, when a ridge stripe portion is provided between the depression 1 and the depression 2 as in, for example, a nitride semiconductor light emitting device (laser device) having a ridge stripe structure shown in FIG. Improved. As a result of investigating this in detail, it was found that cracks crossing the longitudinal direction of the ridge stripe were reduced. This is considered to be because cracks could be prevented from penetrating into the ridge stripe portion of the nitride semiconductor light emitting device by having the depressions on both sides of the ridge stripe portion.

Further, it has been found that the depression in the present invention has the following effects in the electrode of one nitride semiconductor light-emitting device divided into chips. When two or more dents according to the present invention are included in one nitride semiconductor light emitting element, the element defect rate due to electrode peeling is reduced by about 20% as compared with one element. Moreover, when a ridge stripe portion is provided between the depressions 1 and 2 as in a nitride semiconductor light emitting device (laser device) having a ridge stripe structure shown in FIG. p electrode 112
Peeling (including the pad electrode) was prevented, and the yield of the light emitting device was improved. For this reason, it is preferable that the electrode is formed on a region including two or more depressions,
It has been found that a ridge stripe portion is more preferably provided between the depressions, and the electrode is preferably formed on a region including these depressions. The effect of preventing the electrode peeling at the ridge stripe portion was the same for the peeling of the dielectric film. For example, the same applies to the SiO ₂ dielectric film 113 shown in FIG. S
Instead of the iO ₂ dielectric film 113, another dielectric film such as SiN _x may be used.

Further, it has been found that the depression in the present invention has the following effects in wire bonding of one nitride semiconductor element divided into chips. Since one or more dents according to the present invention are included in the bonding region between the wire bond and the nitride semiconductor light emitting device, the peeling of the wire bond itself or the peeling of the electrode including the wire bond is reduced by about 20%. . From this, it was found that it is preferable that one or more dents in the present invention be included in the bonding region between the wire bond and the nitride semiconductor light emitting device.

(Regarding Processed Substrate) The processed substrate in the present invention is constituted by using a nitride semiconductor substrate or a heterogeneous substrate. In particular, when a nitride semiconductor substrate is used as a processing substrate, it is preferable in the following points. That is, since the nitride semiconductor substrate has a small difference in thermal expansion coefficient from the nitride semiconductor base layer formed thereon, the warpage of the substrate is much smaller than in the case where a heterogeneous substrate is used. Therefore, the grooves and hills formed in the nitride semiconductor substrate can be formed with higher precision than those formed in the nitride semiconductor layer on the heterogeneous substrate. Further, as will be described in more detail in the following item (about the formation position of the light emitting portion), since the warpage of the substrate is very small, a region in which an element failure such as a short emission life is likely to occur (a region III and a region III described later) is likely to occur. I
V) can be avoided and the light emitting element structure can be manufactured with high accuracy. Furthermore, the small warpage of the substrate itself acts to prevent the occurrence of new distortion and cracks, and also has the effect of extending the life of the semiconductor laser element and reducing other characteristic defects.

(Regarding the Film Thickness of the Nitride Semiconductor Underlayer Covering the Worked Substrate) In the present invention, in order to form a dent which is not covered with the nitride semiconductor multilayer film structure, for example, a nitride semiconductor The stratum may be grown thin. However, apart from the case where a recess is formed also in the region above the groove, it is difficult to form a light emitting element in the region above the groove unless the groove formed in the processing substrate is buried flat. Therefore, the coating thickness of the nitride semiconductor underlayer is preferably about 2 μm or more and 20 μm or less. When the coating film thickness is smaller than 2 μm, it becomes difficult to completely and flatly bury the groove in the nitride semiconductor base layer, although it depends on the groove width and the groove depth formed in the processed substrate. . On the other hand, if the coating thickness is greater than 20 μm,
In particular, when the processed substrate includes a heterogeneous substrate, the processed substrate and the nitride semiconductor underlayer (or the nitride semiconductor multilayer film structure) are more effective than the effect of alleviating the crystal distortion due to the depression and the effect of suppressing the crack.
The stress-strain due to the difference in thermal expansion coefficient between the two becomes too strong, and the effect of the present invention may not be sufficiently exhibited.

(Regarding Groove Width) A groove formed in a nitride semiconductor substrate is easily buried in a nitride semiconductor base layer if the groove width is relatively small, and is difficult to be buried if it is wide. According to the study results of the present inventors, a groove width G for completely and flatly covering a groove formed on a processed substrate with a nitride semiconductor underlayer.
1 was preferably from 4 μm to 30 μm, more preferably from 4 μm to 25 μm. On the other hand, the groove width G2 for forming the depression without completely covering the groove formed on the processing substrate with the nitride semiconductor base layer is preferably 7 μm or more and 75 μm or less, but is preferably about 7 μm or more and about 75 μm or less. It may be 100 μm or less. However, whether or not a dent is formed above the groove of the processed substrate strongly depends on the coating thickness of the nitride semiconductor underlayer. Therefore, when the groove is completely and flatly covered or a dent is formed in the region above the groove. In doing so, it is necessary to adjust the coating thickness of the nitride semiconductor underlayer together with the groove widths G1 and G2.

The lower limit and the upper limit of the groove width G1 were estimated from the following viewpoints. Groove 1 in which no depression is formed above the groove
The lower limit value of the groove width G1 depends on the size of the light emitting portion in the light emitting element. Regarding the formation position of the light emitting portion in the light emitting element,
FIG.
Will be described in more detail with reference to FIG. For example, when a nitride semiconductor laser device is formed in an upper region of a groove covered with a flat surface in a recessed substrate, the light emitting portion below the ridge stripe portion of the nitride semiconductor laser device is formed as shown in FIG. It preferably belongs to region I in (a). Therefore, at least the lower limit of the groove width G1 is:
It must be wider than twice the ridge stripe width.
Since the ridge stripe width is formed to be approximately 1 μm to 3 μm, the groove width G1 is 4 μm obtained by adding the width 2 μm of the region III in FIG. 7A and the stripe width (1 μm) × 2.
It is estimated that it must be at least.

On the other hand, the upper limit of the groove width G1 exists because
If the groove width G1 exceeds 25 μm, it becomes difficult to completely bury the groove 1 having the groove width G1 by laminating the nitride semiconductor underlayer with a coating thickness of 10 μm or less. Similarly, if the groove width G1 exceeds 30 μm, it becomes difficult to completely bury the groove 1 even if the nitride semiconductor underlayer is laminated to a coating film thickness of 20 μm or more.

The lower limit and the upper limit of the groove width G2 were estimated from the following viewpoints. Similarly to the lower limit of the groove width G1, the lower limit of the groove width G2 of the groove 2 in which the depression is formed above the groove depends on the size of the light emitting portion in the light emitting element. For example, when a nitride semiconductor laser device is manufactured in a region above a groove 2 in which a depression is formed in a groove width G2, the light emitting portion below the ridge stripe portion of the laser device is formed as shown in FIG. It preferably belongs to region II in (b). Ridge stripe width is approximately 1 μm to 3 μm
Since the minimum depression width can be estimated at 1 μm, the lower limit of the groove width G2 is the width of the region IV including the depression = the depression width (1 μm) +2 μm × 2 (see FIG. 7B) and the stripe width ( 1 μm) × 2 and 7 μm or more. However, this is not the case when the nitride semiconductor laser element is not formed so that the ridge stripe portion is completely included in the region above the groove in which the depression is formed, and the groove width G2 in that case is the depression width (1 μm). It is sufficient if the width is equal to or greater than the width, more preferably the width (5 μm) of the region IV including the depression. The meaning of the region IV will be described later with reference to FIG.

On the other hand, the upper limit of the groove width G2 of the groove 2 in which the depression is formed above the groove is not particularly limited from the viewpoint of the laser oscillation life. However, if G2 is too large, the dent density per unit area of the wafer decreases, and the effect of alleviating crystal distortion and the effect of suppressing cracks decrease.
Along with this, the yield of light emitting element chips per wafer also decreases. Therefore, from the above viewpoint, the upper limit of the groove width G2 is 100 μm or less, and more preferably 75 μm or less.

In the above, the processed substrate in which only the groove width is changed has been described. However, it goes without saying that the processed substrate may be formed by changing not only the groove width but also the groove depth and / or the hill width. .

(Groove Depth) A groove formed in a nitride semiconductor substrate is easily buried in a nitride semiconductor underlayer if the depth is relatively shallow, and hard to be buried if it is deep. The formation of the depression by adjusting the groove depth is preferable because the yield of the light emitting element chips per wafer does not decrease as compared with the case where the depression is formed by adjusting the groove width.

According to the study results of the present inventors, the groove depth H1 for completely and flatly covering the groove formed on the processed substrate with the nitride semiconductor base layer is not less than 1 μm and not more than 9 μm. And more preferably 2 μm or more and 6 μm or less. On the other hand, the groove depth H2 for forming a depression without completely covering the groove formed in the processing substrate with the nitride semiconductor base layer is preferably 1 μm or more, more preferably 2 μm or more. I liked it. There is no particular limitation on the upper limit of the groove depth H2.
The remaining thickness h as shown in FIG. However, whether or not a dent is formed above the groove of the processed substrate strongly depends on the coating thickness of the nitride semiconductor underlayer. Therefore, when the groove is completely and flatly covered, or when a dent is formed above the groove. In this case, it is necessary to adjust the coating thickness of the nitride semiconductor underlayer together with the groove depths H1 and H2.

The lower limit and the upper limit of the groove depth H1 were estimated from the following viewpoints. The lower limit of the groove depth H1 of the groove 1 in which no depression is formed above the groove is preferably 1 μm or more, more preferably 2 μm or more. This is because if the groove depth H1 is smaller than 1 μm, the growth in the vertical direction with respect to the main surface of the substrate has priority over the horizontal growth in the crystal growth mode, and the effect of reducing the crystal distortion due to the horizontal growth is reduced. This is because there is a possibility that it will not be sufficiently exhibited. If the lower limit of the groove depth H1 is 2 μm or more, the effect of reducing crystal distortion due to lateral growth can be sufficiently exhibited.

On the other hand, the upper limit of the groove depth H1 is 9 μm.
m or less, and more preferably 6 μm or less. This is because, if the groove depth H1 exceeds 6 μm, it becomes difficult to completely bury the groove 1 having the groove depth H1 by laminating the nitride semiconductor underlayer with a coating thickness of 10 μm or less. . Similarly, the groove depth H
If 1 exceeds 9 μm, the nitride semiconductor underlayer is coated with a film thickness of 2
This is because it becomes difficult to completely bury the groove 1 even if the groove 1 is laminated to a thickness of 0 μm or more.

The lower limit and upper limit of the groove depth H2 were estimated from the following viewpoints. The lower limit of the groove depth H2 of the groove 2 in which the depression is formed above the groove is 1 μm as in the case of the groove depth H1.
m or more, more preferably 2 μm or more. This is because, as described with respect to the groove depth H1, if the effect of reducing the crystal distortion due to the lateral growth is not sufficiently obtained, the characteristics of the light emitting element formed in the region above the groove 2 (for example, the laser oscillation life) may be reduced. This is because there is a possibility that it will decrease. While the lower limit value of the groove depths H2 and H1 is the same, whether a dent is formed in the region above the groove by the nitride semiconductor film or is completely buried is determined by
It depends on the coating thickness of the nitride semiconductor underlayer. On the other hand,
There is no particular limitation on the upper limit of the groove depth H2, and the deeper the groove depth H2, the easier it is to form a depression. However, if the groove 2 is too deep, the processed substrate is likely to be cracked. Therefore, the remaining thickness h between the bottom of the groove and the back surface of the substrate is 100 μm.
m (see FIG. 2A).

In the above, the processed substrate in which only the groove depth is changed has been described. However, it goes without saying that the processed substrate may be formed by changing not only the groove depth but also the groove width and / or the hill width.

(Regarding the hill width) The hill formed on the processed substrate is easily buried in the nitride semiconductor base layer if the hill width is relatively narrow, and hard to be buried if it is wide. According to the study results of the present inventors, the hill width L1 for completely and flatly covering the hill formed on the processed substrate with the nitride semiconductor underlayer is:
4 μm or more and 30 μm or less, preferably 4 μm
More preferably, it is not less than m and not more than 25 μm. On the other hand, a hill width L2 for forming a depression without completely covering the hill formed on the processing substrate with the nitride semiconductor underlayer.
Is preferably 7 μm or more and 75 μm or less,
It may be 7 μm or more and 100 μm or less. However, whether or not a dent is formed above the hill of the processed substrate strongly depends on the thickness of the nitride semiconductor base layer. Therefore, when the hill is completely and flatly covered, or when a dent is formed in the region above the hill. When forming, it is necessary to adjust not only the hill widths L1 and L2 but also the coating thickness of the nitride semiconductor underlayer.

The lower and upper limits of the hill width L1 were estimated from the following viewpoints. Hill 1 where no depression is formed above the hill
The lower limit of the hill width L1 depends on the size of the light-emitting portion in the light-emitting element, similarly to the above-described lower limit of the groove width G1. For example, when a nitride semiconductor laser device is formed in a region of a recessed substrate that is flatly covered above a hill, the light emitting portion below the ridge stripe portion of the laser device has a recess from the viewpoint of laser oscillation life. In the region I where no pattern is formed (FIG. 7)
(B)). The ridge stripe width is about 1 μm to 3 μm, and the width of the region III when no depression is formed above the hill can be estimated to be 2 μm. Therefore, the lower limit of the hill width L1 is stripe width (1 μm) × 2. 4 μm obtained by adding 2 μm width of region III
It is necessary to be above. On the other hand, the upper limit of the hill width L1 can be estimated in the same manner as the above-described upper limit of the width of the groove 1.

Further, the lower limit and the upper limit of the hill width L2 were estimated as follows. The lower limit of the hill width L2 of the hill 2 in which no depression is formed on the hill depends on the size of the light emitting portion in the light emitting element, similarly to the above lower limit of the groove width G2.
For example, when a nitride semiconductor laser device is formed in an area above a hill 2 having a hill width L2 including a depression, the light emitting portion below the ridge stripe portion of the laser device is shown in FIG. It preferably belongs to region II in the middle. The ridge stripe portion is formed with a width of about 1 to 3 μm, and the minimum depression width can be estimated at 1 μm. Therefore, the lower limit of the hill width L2 is the width of the region IV including the depression = the depression width (1 μm) +2 μm × 2. And stripe width (1 μm) ×
2 plus 7 μm. However,
This is not the case when the nitride semiconductor laser element is not formed so that the ridge stripe portion is completely included in the area above the hill 2 where the depression is formed. In this case, the hill width L2 is not less than the depression width (1 μm). It is preferable that the width be equal to or more than the width (5 μm) of the region IV including the depression. On the other hand, the upper limit value of the hill width L2 of the hill 2 where the depression is formed above the hill is not particularly limited from the viewpoint of the laser oscillation life. However, for the same reason as the upper limit of the groove width G2 of the groove 2, the upper limit of the hill width L2 is 100 μm or less, more preferably 75 μm or less.

In the above, the processed substrate in which only the hill width is changed has been described. However, it goes without saying that the processed substrate may be formed by changing not only the hill width but also the groove width and / or the groove depth.

(With respect to the longitudinal direction of the groove) As a main surface, $ 0
The longitudinal direction of a groove formed in a nitride semiconductor substrate having a 001 ° C. plane or a nitride semiconductor layer on a heterogeneous substrate is <1.
Most preferably, it is parallel to the <-100> direction.
It was next preferred to be parallel to the 1-20> direction.
The longitudinal direction of the groove in these specific directions is $ 000
Even if it had an opening angle of about ± 5 ° within the 1 ° C plane, no substantial influence was caused.

The advantage of forming a groove along the <1-100> direction of the nitride semiconductor crystal is that the depression is difficult to fill, and the effect of suppressing crystal distortion and crack generation is extremely high. When a nitride semiconductor underlayer grows in a groove formed along this direction, a {11-20} plane is likely to be mainly formed as a side wall surface of the depression. This $ 11-2
Since the 0 ° side wall surface is perpendicular to the main surface of the substrate as shown in FIG. 8A, the depression tends to have a substantially rectangular cross section. When the cross section of the depression is close to a rectangular shape, it is difficult for the raw material constituting the nitride semiconductor to be supplied to the depth of the depression, and the groove is hard to be filled with the nitride semiconductor underlayer. For this reason, even if the processed substrate is relatively thickly covered with the nitride semiconductor underlayer, there is no fear that the dent is buried. In addition, since the cross section of the dent is rectangular and is difficult to be filled, the depth of the dent becomes extremely deeper than that of the dent having the {1-101} sidewall surface described below (the depth of the groove formed in the processing substrate is substantially maintained). In addition, the crystal distortion of the nitride semiconductor underlayer grown on the processed substrate is alleviated by the deep depression, and the generation of cracks can be effectively suppressed.

On the other hand, the nitride semiconductor crystal <11-20>
The advantage of forming the groove along the direction is that the shape of the depression is steep and the fluctuation of the position of the depression is small. When the nitride semiconductor underlayer grows in the trench formed along this direction, the side wall surface of the dent mainly becomes {1-1}.
The 01 ° plane is easily formed. Since the {1-101} side wall surface is very flat and the edge portion (see FIG. 3) is steep and does not meander, the dent along the <11-20> direction is also straight and hard to meander. Therefore, the regions I and II for forming a light-emitting element having a long light-emitting life, which will be described later, can be widened (improving the yield of the light-emitting element), and a decrease in the element yield due to a misaligned laser element formation position can be prevented. can do.

Although the above-mentioned grooves or hills are all stripe-shaped, the stripe-shaped one is preferable in the following points. That is, the portion contributing to the oscillation of the nitride semiconductor laser device (below the ridge stripe portion) has a stripe shape, and if the preferable ridge stripe portion forming regions I and II are also in a stripe shape, the portion contributing to the oscillation is represented by the stripe. It is easy to make it into the preferred region I or II. It is preferable that the grooves or hills have a mesh shape in that the crystal distortion can be alleviated uniformly in the substrate surface and the crack suppressing effect is high. For example, as shown in FIG. 5, the grooves may be formed in a mesh shape.

FIG. 5A is a top view of a processed substrate having a concave portion and a convex portion when two different types of groove directions are formed so as to be orthogonal to each other. FIG. 5 (b)
Shows a top view of a processed substrate having a concave portion and a convex portion when two different types of groove directions are formed so as to form an angle of 60 degrees with each other. And FIG. 5 (c)
FIG. 4 shows a top view of a processed substrate having a concave portion and a convex portion when three different types of groove directions are formed so as to form an angle of 60 degrees with each other.

(Regarding Nitride Semiconductor Underlayer) As the underlayer made of a nitride semiconductor film covering the processed substrate, for example, a GaN film, an AlGaN film, an InGaN film, or the like can be used. Further, Si, O, Cl, S, C, Ge, Zn, Cd, Mg
And at least one impurity in the impurity group of Be can be added.

If the nitride semiconductor underlayer is a GaN film,
It is preferable in the following points. That is, since the GaN film is a binary mixed crystal, the controllability of crystal growth is good. Further, since the surface migration length of the GaN film is longer than that of the AlGaN film and shorter than that of the InGaN film, the portion where the trench is to be filled and flattened is appropriately covered with the GaN film, and the portion where the depression is to be formed is made of the GaN film. Coating is moderately limited. The impurity concentration of the GaN film used as the nitride semiconductor underlayer is 1 × 10 ¹⁷ / cm ³ or more and 5 × 10 ¹⁸
/ Cm ³ or less. If the impurity is added in such a concentration range, the surface morphology of the nitride semiconductor underlayer becomes good, and as a result, the thickness of the light emitting layer can be made uniform and the device characteristics can be improved.

If the nitride semiconductor underlayer is an AlGaN film, it is preferable in the following points. Since the AlGaN film contains Al, the surface migration length is shorter than that of the GaN film or the InGaN film. The fact that the surface migration length is short means that the cross section of the dent maintains a steep state (for example, the edge in FIG. 3 does not drop), and the nitride semiconductor does not easily flow into the bottom of the dent (the dent is difficult to fill). ) Means that. In addition, even when the trench is covered, the nitride semiconductor does not easily flow into the bottom of the trench, and the crystal growth from the sidewall of the trench is promoted, so that the lateral growth becomes remarkable and the crystal distortion is further reduced. Becomes possible. The Al composition ratio x of the Al _x Ga ₁ -xN film is 0.01
The above is preferably 0.15 or less, more preferably 0.01 or more and 0.07 or less. If the composition ratio x of Al is smaller than 0.01, the above-mentioned surface migration length may be increased. On the other hand,
If the composition ratio x of Al is larger than 0.15, the surface migration length may be too short, and it may be difficult to fill a groove to a region to be flattened. In addition, an effect equivalent to that of the AlGaN film is obtained as long as the nitride semiconductor underlayer contains Al. In addition, AlG used as a nitride semiconductor underlayer is used.
The impurity concentration of the aN film is 5 × when the impurity concentration is 3 × 10 ¹⁷ / cm ³ or more.
It is preferably 10 ¹⁸ / cm ³ or less. If an impurity is added simultaneously with Al in such a concentration range, the surface migration length of the nitride semiconductor underlayer is preferably reduced. This makes it possible to further reduce crystal distortion.

If the nitride semiconductor underlayer is an InGaN film, it is preferable in the following points. Since the InGaN film contains In, it is more elastic than a GaN film or an AlGaN film. Therefore, the InGaN film is buried in the groove of the processing substrate, and has a function of diffusing crystal strain from the substrate throughout the nitride semiconductor multilayer film structure, thereby effectively relaxing crystal distortion. The In composition ratio x of the In _x Ga ₁ -xN film is preferably 0.01 or more and 0.15 or less, and more preferably 0.01 or more and 0.1 or less. If the composition ratio x of In is smaller than 0.01, In
, It may be difficult to obtain the elasticity effect. If the composition ratio x of In is larger than 0.15, the crystallinity of the InGaN film may be reduced. In addition, an effect equivalent to that of the InGaN film is not limited to the InGaN film, and can be obtained if the nitride semiconductor underlayer contains In. Further, the impurity concentration of the InGaN film used as the nitride semiconductor underlayer is preferably 1 × 10 ¹⁷ / cm ³ or more and 4 × 10 ¹⁸ / cm ³ or less. It is preferable that the impurity be added simultaneously with In in such a concentration range because the surface morphology of the nitride semiconductor underlayer is good and the nitride semiconductor can have elasticity.

(Regarding the formation position of the light emitting portion) As a result of a detailed study by the present inventors, the position of the light emitting portion (below the ridge stripe portion) of the nitride semiconductor laser device formed on the recessed substrate is determined. It has been found that the laser oscillation lifetime varies depending on the laser oscillation lifetime. Here, the light emitting portion is a portion of the light emitting layer which substantially contributes to light emission when a current is injected into the light emitting element. For example, in the case of a nitride semiconductor laser device having a ridge stripe structure, it is a light-emitting layer portion below a ridge stripe portion into which current is confined and injected.

In FIG. 6, the horizontal axis of the graph represents the distance from the groove center c of the recessed substrate to the ridge stripe end a in the width direction, and the vertical axis represents the laser output of 30 mW and the ambient temperature of 60 ° C. It shows the laser oscillation life. Here, the distance from the groove center c to the ridge stripe end a (hereinafter referred to as c-a distance) is indicated such that the right side in the width direction from the groove center c is positive and the left side is negative. FIG.
The structure and manufacturing method of the nitride semiconductor laser device measured in the above were the same as in Embodiment 8 described later, a GaN processed substrate was used, the ridge stripe width was 2 μm, and the groove width was 18 μm.
m, the hill width was 15 μm, and the dimple width above the hill was 3 μm.

As can be seen from FIG. 6, the laser oscillation lifetime of a nitride semiconductor laser device having a ridge stripe formed above a groove tends to be longer than that of a nitride semiconductor laser device having a ridge stripe formed above a hill. Indicated. Further investigation revealed that, even in the region above the groove, if the ridge stripe portion was formed in a region where the ca distance was larger than -3 μm and smaller than 1 μm, the laser oscillation life was dramatically improved. It was found to decrease. Here, taking into account that the width of the ridge stripe portion is 2 μm, the c−a distance−
If 3 μm is converted into the distance from the groove center “c” to the ridge stripe end “b” (hereinafter referred to as “c−b distance”), the c−b distance becomes −1 μm. That is, when at least a part of the ridge stripe portion of the nitride semiconductor laser element is formed so as to be included within a range of less than 1 μm in the width direction from the groove center c to the left and right, the laser oscillation life is dramatically reduced. I understand.

Region where the laser oscillation life is dramatically reduced (range of less than 1 μm in the width direction from the center c of the groove).
Will be referred to as a region III. Therefore, it is preferable that the ridge stripe portion of the nitride semiconductor laser element be formed so as to include the entire area (ab width) in a range excluding the region III. Here, within the groove width range, a range of 1 μm or more in the width direction from the groove center c in the width direction is referred to as a region I. The region I is a region where a nitride semiconductor laser device having a longer laser oscillation life can be formed than the region II described below, and is the most preferable region among the recessed substrates.

On the other hand, also in the area above the hill, similar to the area above the groove, the ca distance is larger than 11 μm and 2
It can be seen that when the light emitting portion of the nitride semiconductor laser device is formed in a region smaller than 0 μm, the laser oscillation life is dramatically reduced. Here, when the state of the ca distance of 11 μm is represented by the distance from the dent end d to the ridge stripe end b, it is 2 μm. Similarly, the state of the ca distance of 20 μm is from the dent end e to the ridge stripe end a. If expressed as a distance, it will be 2 μm. That is, when at least a part of the light emitting portion below the ridge stripe portion is included within a range of 2 μm from both sides of the dent end to the outside, the laser oscillation life is dramatically reduced. The region where the laser oscillation life is dramatically reduced is referred to as IV. Therefore, in the region above the hill, the concave end d excluding the region IV
It is preferable that the entire ridge stripe portion (ab) is formed to be included in a range of 2 μm or more on the left side in the width direction or 2 μm or more on the right side of the concave end e. Here, in a region above the hill, a region that is 2 μm or more to the left in the width direction from the dent end d and 2 μm or more to the right from the dent end e is referred to as a region II. In this region II, a nitride semiconductor laser device having a lifetime of several thousand hours can be formed although the laser oscillation life is shorter than that of the above-mentioned region I.

In FIG. 7, the above-mentioned regions I to IV are shown in a schematic sectional view of the substrate having a depression. That is, the light emitting portion of the nitride semiconductor laser device fabricated on the recessed substrate is preferably formed at a position avoiding at least the regions III and IV, of which the region I is the most preferable, and the region II is the most preferable. Then it was preferred (see Figure 6).

FIG. 7A shows a case in which a depression is formed only in the region above the hill. For example, as in Embodiments 5 to 7 described later, the region above the hill is nitrided. As shown in FIG. 7B, the range of the region I when completely and flatly covered with the semiconductor underlayer is in the region above the hill and from the center of the hill to the right or left in the width direction. The region was 1 μm or more apart. This is because if the light emitting portion is formed so as to be included in a range of 1 μm to the left and right from the center of the hill (region III where no depression is formed above the hill), the laser oscillation life is dramatically reduced. It is.

Similarly, in FIG. 7A, no dent is formed above the groove. However, for example, when a dent is formed above the groove as in Embodiments 3, 6, and 7 described later. The region II was a region within the region above the groove and separated from both ends of the recess by 2 μm or more in the width direction to both outsides (see FIG. 7B). This is because the laser oscillation life is dramatically reduced if the light emitting portion is formed so as to be included within a range of 2 μm left and right from both ends of the recess (region IV when the recess is provided above the groove). Because.

It should be noted that the same tendency as in FIG. 6 was exhibited even when the groove width, the hill width, and the ridge stripe width were variously changed. In addition, when the processing substrate was changed from a GaN substrate to a substrate including a heterogeneous substrate, the laser oscillation life was shorter than that of the GaN substrate, but the same tendency as in FIG. 6 was shown. Therefore, also in these cases, it is considered that the light emitting portion forming region of the light emitting element to be formed on the recessed substrate has the relationship shown in FIG. Similarly, a light emitting diode (LE
D) With respect to the element, the effect of the present invention can be obtained as long as one of the regions I and II shown in FIG. 7 exists below the light emitting portion into which the current is injected.

Although the nitride semiconductor laser device in FIG. 6 has a ridge stripe structure, a nitride semiconductor laser device having a current blocking structure can obtain the same tendency as in FIG. (In the case of the current blocking structure, the ridge stripe portion in FIG. 6 corresponds to the current confined portion, and the ridge stripe width corresponds to the current confined width). That is, in the nitride semiconductor laser device, current is confinedly injected into the light emitting layer, and the region I shown in FIG.
Or any of II may be present.

However, in the case of the nitride semiconductor laser device having the current blocking structure, the laser oscillation lifetime is about 2 times that of the device having the ridge stripe structure described above.
It was about 0-30% lower. Further, the nitride semiconductor laser device having the current blocking structure has a large decrease in the yield due to the occurrence of cracks as compared with the device having the ridge stripe structure. Although the causes are not clear, it is conceivable that the current confining portion is formed in the current blocking layer, and the nitride semiconductor layer is crystal-grown again on the current blocking layer in which the current blocking portion is formed. There may be a problem. For example, in the step of forming a current confined portion in the current blocking layer, a mask material such as a resist material is used, and these mask materials are adhered in the depressions of the nitride semiconductor light emitting device according to the present invention. It is considered that the regrowth as it was had an adverse effect on the characteristics of the light emitting device. Further, for example, in the step of crystal-growing a nitride semiconductor again on the current blocking layer in which the current confined portion has been formed, the crystal growth is performed once during the fabrication of the light emitting element structure in order to form the current confined portion in the current blocking layer. It is taken out of the apparatus (at room temperature) and loaded into the crystal growth apparatus again to grow the remaining light emitting element structure into a crystal (about 1000).
° C). As described above, if a thermal history having a sharp temperature difference is given during the fabrication of the light emitting device structure, even if the nitride semiconductor light emitting device according to the present invention has a dent, the crystal in the light emitting device structure is caused by the dent. It is considered that the strain is not sufficiently relaxed and cracks occur.

[Embodiment 2] In Embodiment 2, a method of manufacturing a substrate with a dent according to the present invention will be described with reference to FIGS. Note that items not specifically mentioned in the present embodiment are the same as those in the first embodiment. 3A and 3B show names of respective parts of the substrate with depressions, FIG. 8A shows a substrate with depressions when the cross-sectional shape of the depressions is rectangular, and FIG. The figure shows a substrate with a depression in the case of an inverted trapezoidal shape (a V-shaped shape as crystal growth proceeds further).

The processing substrate shown in FIG. 8 can be manufactured as follows. First, a dielectric film such as SiO ₂ or SiN _x was deposited on the surface of an n-type GaN substrate having a (0001) principal plane orientation. Then, a resist material was applied to the dielectric film using a normal lithography technique, and the resist material was formed into a stripe-shaped mask pattern.
Along the mask pattern, a groove was formed by etching a part of the surface of the dielectric film and the GaN substrate using a dry etching method. After that, the resist material and the dielectric film were removed. The grooves and hills thus formed were along the <1-100> direction of the n-type GaN substrate, and had a groove width of 18 μm, a groove depth of 3 μm, and a hill width of 7 μm. A low-temperature GaN buffer layer is formed at a relatively low temperature of about 500 to 600 ° C. on a sapphire substrate having a (0001) principal plane orientation, and then an n-type GaN layer is formed on the low-temperature GaN buffer layer. After that, a processed substrate may be manufactured using the same method as described above (see FIG. 2B).

The processed substrate thus produced is sufficiently washed with an organic material, and then carried into an MOCVD (metal organic chemical vapor deposition) apparatus, where a nitride semiconductor base layer made of an n-type GaN film having a coating thickness of 6 μm is laminated. Was done. In forming the n-type GaN underlayer, NH ₃ (ammonia) as a group V element source and TMGa (trimethylgallium) or TMG as a group III element source are placed on a processing substrate set in a MOCVD apparatus.
EGa (triethyl gallium) is supplied and 1050 ° C
At the crystal growth temperature, SiH ₄ (S
i impurity concentration 1 × 10 ¹⁸ / cm ³ ) was added.

FIG. 8A is a schematic cross-sectional view of a substrate with a depression manufactured by the above-described method. As can be seen from the figure, a depression was formed only in the region above the hill under the above growth conditions, and the groove was buried flat by the n-type GaN underlayer. The depression was formed such that the center position of the hill width and the center position of the depression width almost coincided with each other. Furthermore, the cross-sectional shape of the depression when the groove was formed along the <1-100> direction of the GaN crystal was almost close to a rectangular shape.

The nitride semiconductor light emitting device according to the present invention is formed on the recessed substrate thus manufactured.

In addition to the above-described groove forming method in the present embodiment, a processed substrate may be manufactured by directly applying a normal resist material on the surface of the nitride semiconductor substrate. However, as described above, it was preferable to form the groove via the dielectric film because the shape of the groove was steep.

When a processed substrate including a heterogeneous substrate (for example, a sapphire substrate) is used as shown in FIG. 2B, the low-temperature GaN buffer layer may be a low-temperature AlN buffer layer. Here, the low-temperature buffer layer means a buffer layer formed at a growth temperature of about 500 to 600 ° C. as described above. The buffer layer formed in such a relatively low growth temperature range was amorphous or polycrystalline. However, SiC or S
In the case of using i, a high-temperature nitride semiconductor buffer layer containing at least Al (a growth temperature of 700 to 10
(00 ° C.) is not preferred because the crystallinity of the nitride semiconductor layer grown on the buffer layer is reduced.

In this embodiment, the low-temperature GaN
N-type GaN layer is grown on the buffer layer (nitride semiconductor underlayer) is not limited to this, Al _x Ga _y In _z N
(0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z ≦ 1; x + y + z =
1) It may be a layer, Si, O, Cl, S, C, G
e, Zn, Cd, Mg, or Be may be doped.

In this embodiment, the groove forming method by the dry etching method has been exemplified. However, it goes without saying that other groove forming methods may be used. For example, a wet etching method, a scribing method, a wire saw process, an electric discharge process, a sputtering process, a laser process, a sand blast process, a focus ion beam process, or the like can be used.

In this embodiment, <1-10 of the GaN crystal
Although the groove is formed along the <0> direction, the groove may be formed along the <11-20> direction. <11 of GaN crystal
When the grooves were formed along the -20> direction, as shown in FIG. 8B, the cross-sectional shape of the depression was close to an inverted trapezoidal shape. However, if the bottom of the dent is buried, the cross-sectional shape becomes close to a V-shape.

In the present embodiment, (0001)
Although a GaN substrate or a sapphire dissimilar substrate having a plane is used, other plane orientations or other dissimilar substrates may be used. The numerical values of the groove width, the hill width, and the groove depth formed on the processing substrate described in the present embodiment and the numerical value of the coating thickness of the nitride semiconductor underlayer are the same as those in the first embodiment. Other numerical values may be adopted as long as the numerical range conditions described above are satisfied. This is the same in other embodiments.

[Embodiment 3] In Embodiment 3, a method for manufacturing a substrate having a depression not only above a hill but also above a groove will be described with reference to FIG. Note that items not specifically mentioned in the present embodiment are the same as those in the above-described first and second embodiments.

That is, the processed substrate and the nitride semiconductor underlayer (GaN underlayer in this embodiment) in FIG. 9 are manufactured in the same manner as in the second embodiment. However, the coating thickness of the GaN underlayer was relatively thin, and was 3 μm.

Since the recessed substrate has a depression not only above the hill but also above the groove, as described in the previous item (the crystal growth mode in the present invention), the crystal formed by the lateral growth is formed. GaN with no crystal strain concentration due to collisions and almost alleviated crystal strain
It can be coated with an underlayer.

The nitride semiconductor light emitting device according to the present invention is manufactured on the substrate with the hollow thus manufactured.

The substrate with a depression in the third embodiment can be easily obtained mainly by adjusting the thickness of the GaN underlayer that covers the processed substrate to be small.

[Embodiment 4] In Embodiment 4, except that the hill width formed on the processing substrate is not a fixed value but various different values,
Is the same as

FIG. 10 is a schematic cross-sectional view showing a substrate having a depression in the present embodiment, and the groove width G1 is 12 μm.
m, groove depth H1 is 3 μm, and only hill width is L1 = 8 μm
m and L2 = 14 μm. A nitride semiconductor base layer made of an InGaN film having a coating thickness of 5 μm was laminated on such a processed substrate to produce a substrate with depressions according to the fourth embodiment.

The nitride semiconductor light emitting device according to the present invention is formed on the recessed substrate thus manufactured.

As can be seen from FIG. 10, by varying the width of the hill formed on the processing substrate, the depression 2 formed above the relatively wide hill 2 is formed above the narrow hill 1. It tends to be larger than the recess 1 that is formed. A relatively large dent has a greater effect of alleviating crystal distortion and suppressing cracks than a small dent. A recessed substrate including recesses having different sizes as in the present embodiment is preferable in the following points.

In other words, a relatively small dent among the pitted substrates can form a light emitting element having a long laser oscillation life, although the effect of alleviating crystal distortion and the effect of suppressing cracks are smaller than that of a large dent. This is preferable because it is possible to widen the appropriate regions (regions I and II in FIG. 7) (the yield of the light emitting element chip is increased). On the other hand, a relatively large dent in a substrate with a dent reduces the generation of residual crystal distortion and cracks, which cannot be suppressed by a small dent, although the area where a light emitting element with a long laser oscillation life can be formed becomes narrow. This is preferable because the yield of the light emitting element chips can be increased. That is, it can be seen that the substrate with depressions of the present embodiment is preferable from the viewpoint of productivity and yield.

In the present embodiment, two types of processed substrates having different hill widths are illustrated, but it is needless to say that two or more types of processed substrates having different hill widths may be used.

[Fifth Embodiment] In the fifth embodiment, the width of the hill formed in the processing substrate is set to various different values instead of the constant value. Embodiment 4 is the same as Embodiment 4 except that (see FIG. 10) is completely and flatly covered with the nitride semiconductor film. In addition, matters not specifically mentioned in the present embodiment are the same as those in the above-described first and second embodiments.

FIG. 11 is a schematic cross-sectional view showing a substrate with a dent in this embodiment. The groove width G1 is 16 μm.
The groove depth H1 was 2 μm, and only the hill width had two values, L1 = 4 μm and L2 = 24 μm. An AlGaN film having a coating thickness of 4 μm was laminated on such a processed substrate, and a substrate with depressions according to the fifth embodiment was manufactured.

The nitride semiconductor light emitting device according to the present invention is formed on the recessed substrate thus manufactured.

As can be seen from FIG. 11, by changing the width of the hill formed on the processing substrate in various ways, the depression 2 is formed above the relatively wide hill 2 and the relatively narrow hill 2 is formed. The upper part of 1 is completely and flatly buried with a nitride semiconductor base layer made of an AlGaN film. Such a recessed substrate in the present embodiment is preferable in the following points.

That is, since no depression is formed above the hill 1 in the substrate with depressions, it is possible to form a light emitting element having a long laser oscillation life, although the effect of alleviating crystal distortion and the effect of suppressing cracks are small. Area is Embodiment 4
(The yield rate of the light-emitting element chip is increased). On the other hand, among the substrates with depressions, the depressions 2 formed above the hills 2 have an effect of alleviating crystal distortion and an effect of suppressing cracks (increase in the yield of light emitting element chips). Therefore, among the hills formed on the processed substrate, a dent-formed substrate in which a dent is not formed above some hills and a dent is formed above other hills is an embodiment from the viewpoint of productivity. 4 is preferable.

In this embodiment, two types of processed substrates having different hill widths have been exemplified, but it is needless to say that processed substrates having two or more types of different hill widths may be used.

[Embodiment 6] Embodiment 6 is the same as Embodiments 1 and 2 except that the depth of the groove formed in the processed substrate is not a fixed value but various different values. It is.

FIG. 12 is a schematic cross-sectional view showing a substrate having a depression according to the present embodiment. The groove width G1 is 18 μm.
The hill width L1 is 5 μm, and only the groove depth is H1 = 2.5 μm.
m and H2 = 10 μm. A nitride semiconductor base layer made of a GaN film having a coating thickness of 6 μm was laminated on such a processed substrate to produce a recessed substrate of the sixth embodiment.

The nitride semiconductor light-emitting device according to the present invention is formed on the thus-formed substrate with depressions.

As can be seen from FIG. 12, the recess 2 is formed only above the relatively deep groove 2 by variously changing the depth of the groove formed in the processing substrate. The recessed substrate in the present embodiment is preferable in the following points.

That is, since no dent is formed above the recessed substrate except for the groove 2, a light emitting element having a long laser oscillation life can be formed although the effect of alleviating crystal distortion and the effect of suppressing cracks are small. The possible area can be widened (the yield of the light emitting element chip is increased). On the other hand, the depression 2 formed above the groove 2 in the substrate with depression has an effect of alleviating crystal distortion and an effect of suppressing cracks. Therefore, a recessed substrate in which a depression is formed above some of the grooves formed on the processing substrate and no depression is formed on the other grooves, from the viewpoint of the productivity of light emitting element chips. preferable.

In the present embodiment, two types of processed substrates having different groove depths are exemplified. However, it is needless to say that processed substrates having two or more types of different groove depths may be used. Further, the present embodiment is similar to the above-described third to fifth embodiments.
Needless to say, it may be combined with at least one of the above.

[Embodiment 7] In Embodiment 7, except that the groove width formed on the processed substrate is not a fixed value but various different values,
Is the same as

FIG. 13 is a schematic cross-sectional view showing a substrate with a depression in this embodiment, in which the hill width L1 is 5 μm,
The groove depth H1 is 4 μm, and only the groove width is G1 = 12 μm
And G2 = 24 μm. A nitride semiconductor base layer made of a GaN film having a coating film thickness of 6 μm was laminated on such a processed substrate to produce a recessed substrate of the seventh embodiment.

Then, the nitride semiconductor light emitting device according to the present invention is formed on the recessed substrate thus manufactured.

As can be seen from FIG. 13, the recess 2 is formed only above the relatively wide groove 2 by variously changing the width of the groove formed in the processing substrate. The recessed substrate according to the present embodiment has the same effects as those of the sixth embodiment.

In this embodiment, two types of processed substrates having different groove widths are exemplified. However, it is needless to say that two or more types of processed substrates having different groove widths may be used. It is needless to say that this embodiment may be combined with at least one of the above-described third to sixth embodiments.

[Eighth Embodiment] In the eighth embodiment, a nitride semiconductor laser device is manufactured on any one of the recessed substrates in the first to seventh embodiments.

(Crystal Growth) FIG. 1 shows a nitride semiconductor laser device after a wafer of a nitride semiconductor laser grown on a recessed substrate is divided into chips. The nitride semiconductor laser device shown in FIG.
N substrate) 101 and n-type Al _0.05 Ga _0.95 N underlayer 102
Recessed substrate 100 of n-type In _0.07 Ga _0.93 N
Crack preventing layer 103, n-type Al _0.1 Ga _0.9 N cladding layer 104, n-type GaN light guide layer 105, light emitting layer 10
6, p-type Al _0.2 Ga _0.8 N carrier block layer 107,
p-type GaN optical guide layer 108, p-type Al _0.1 Ga _0.9 N cladding layer 109, p-type GaN contact layer 110, n-electrode 111, p-electrode 112 and SiO ₂ dielectric film 113
Contains.

In manufacturing such a nitride semiconductor laser device, first, the substrate 100 with a depression according to any one of Embodiments 1 to 7 was formed. However, in Embodiment 8, the groove direction was formed along the <1-100> direction of the GaN substrate.

Next, using a MOCVD apparatus, NH.sub.
₃ (Ammonia) and TMGa (trimethylgallium) or TEGa (triethylgallium) as a raw material for a group III element, TMIn (trimethylindium) as a raw material for a group III element and SiH ₄ (silane) as an impurity are added at 800 ° C. At the crystal growth temperature of n-type In _0.07 Ga _0.93
An N crack preventing layer 103 was grown to a thickness of 40 nm. Next, the substrate temperature is increased to 1050 ° C., and TMAl (trimethylaluminum) or TEAl (triethylaluminum) as a raw material for a group III element is used.
0.9 μm thick n-type Al _0.1 Ga _0.9 N clad layer 10
4 (Si impurity concentration 1 × 10 ¹⁸ / cm ³ ) was grown, and then the n-type GaN optical guide layer 105 (Si impurity concentration 1 × 10 ¹⁸ / cm ³ ) was grown to a thickness of 0.1 μm. .

After that, the substrate temperature is lowered to 800 ° C.
A light emitting layer (multiple quantum well structure) 106 in which an In _0.01 Ga _0.99 N barrier layer having a thickness of 8 nm and an In _0.15 Ga _0.85 N well layer having a thickness of 4 nm were alternately laminated was formed. In this embodiment, the light emitting layer 106 has a multiple quantum well structure starting at the barrier layer and ending at the barrier layer, and includes three (three periods) quantum well layers. In addition, S is added to both the barrier layer and the well layer.
i impurity was added at a concentration of 1 × 10 ¹⁸ / cm ³ . Note that a crystal growth interruption period of 1 second or more and 180 seconds or less may be inserted between the barrier layer and the well layer or between the well layer and the barrier layer. This is preferable because the flatness of each layer is improved and the half width of the emission spectrum is reduced.

When As is added to the light emitting layer 106, AsH ₃ or TBAs (tert-butylarsine) is used.
And when P is added, PH ₃ or TBP
(Tertiary butyl phosphine) and, if Sb is added, TMSb (trimethylantimony)
Alternatively, TESb (triethylantimony) may be used. Further, when the light emitting layer is formed, N material is
N ₂ H ₄ (dimethylhydrazine) may be used in addition to H ₃ .

Next, the temperature of the substrate is again raised to 1050 ° C., and a p-type Al _0.2 Ga _0.8 N carrier block layer 107 having a thickness of 20 nm, a p-type GaN optical guide layer 108 having a thickness of 0.1 μm, and a A 0.5 μm p-type Al _0.1 Ga _0.9 N cladding layer 109 and a 0.1 μm thick p-type GaN contact layer 110 were sequentially grown. As the p-type impurity, Mg (EtCP ₂ Mg: bisethylcyclopentadienyl magnesium) is 5 × 10 ¹⁹ / cm ³ to 2 × 1.
It was added at a concentration of 0 ²⁰ / cm ³ . It is preferable that the p-type impurity concentration of p-type GaN contact layer 110 be increased as approaching the interface with p-electrode 112. By doing so, the contact resistance at the interface with the p-electrode is reduced. Further, a small amount of oxygen may be mixed during the growth of the p-type layer in order to remove residual hydrogen in the p-type layer which is preventing activation of Mg which is a p-type impurity.

After the p-type GaN contact layer 110 is thus grown, all the gases in the reactor of the MOCVD apparatus are changed to nitrogen carrier gas and NH ₃ ,
The substrate temperature was cooled at a cooling rate of 0 ° C./min. When the substrate temperature was cooled to 800 ° C., the supply of NH ₃ was stopped, and the substrate temperature was maintained for 5 minutes and then cooled to room temperature. The holding temperature of this substrate is from 650 ° C. to 900
° C, and the holding time is 3 minutes or more and 1 hour.
Preferably, it was less than 0 minutes. Further, the cooling rate to room temperature is preferably 30 ° C./min or more. The crystal growth film thus formed was evaluated by Raman measurement. As a result, even if the conventional p-type annealing was not performed, the growth film had already exhibited p-type characteristics (that is, Mg was activated). Had been turned). Also, the p electrode 112
The contact resistance at the time of forming was also reduced. In addition to this, if conventional p-type annealing is combined, Mg
The activation rate was further improved, which was favorable.

In the crystal growth step according to the present embodiment, the crystal may be continuously grown from the processed substrate to the nitride semiconductor laser device, or the growth step from the processed substrate to the recessed substrate may be performed in advance. Regrowth for growing the nitride semiconductor laser device may be performed later.

In the present embodiment, the In _0.07 Ga _0.93 N crack preventing layer 103 may have an In composition ratio other than 0.07, or the InGaN crack preventing layer may be omitted. However, when lattice mismatch between the cladding layer and the GaN substrate becomes large, it is preferable to insert an InGaN crack prevention layer.

Although the light-emitting layer 106 of this embodiment starts with a barrier layer and ends with a barrier layer, the light-emitting layer 106 may start with a well layer and end with a well layer. Further, the number of well layers in the light emitting layer is not limited to the three layers described above. If the number of layers is 10 or less, the threshold current value becomes low and continuous oscillation at room temperature was possible. In particular, when the number of well layers is 2 or more and 6 or less, the threshold current value is preferably reduced.

In the light emitting layer 106 of this embodiment, Si is added to both the well layer and the barrier layer at a concentration of 1 × 10 ¹⁸ / cm ³ , but Si may not be added. However, the emission intensity was higher when Si was added to the light emitting layer. The impurity added to the light emitting layer is not limited to Si, and at least one of O, C, Ge, Zn, and Mg may be added. The total amount of impurities added was preferably about 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ . Further, the layer to which the impurity is added is not limited to both the well layer and the barrier layer, and the impurity may be added to only one of these layers.

In the p-type Al _0.2 Ga _0.8 N carrier block layer 107 of the present embodiment, the Al composition ratio may be other than 0.2, or the carrier block layer may be omitted. However, the threshold current value was lower when the carrier block layer was provided. This is because the carrier block layer 107 has a function of confining carriers in the light emitting layer 106. It is preferable to increase the Al composition ratio of the carrier block layer because this increases the confinement of carriers. Conversely, it is preferable to reduce the Al composition ratio within a range in which the confinement of carriers is maintained, because the carrier mobility in the carrier block layer increases and the electric resistance decreases.

In this embodiment, the p-type cladding layer 109 and
Al as the n-type cladding layer 104 _0.1Ga_0.9N crystal
Although it was used, even if its Al composition ratio was other than 0.1
Good. If the mixed crystal ratio of Al increases,
The energy gap difference and the refractive index difference increase,
And light are efficiently confined in the light emitting layer, causing laser oscillation.
The threshold current value can be reduced. Conversely, carriers and light
The Al composition ratio within the range where the confinement of
Then, the carrier mobility in the cladding layer increases,
The operating voltage of the device can be reduced.

The thickness of the AlGaN cladding layer is 0.7 μm
It is preferably within a range of about 1.5 μm, which makes the vertical and lateral modes unimodal and increases the light confinement efficiency, thereby improving the optical characteristics of the laser and reducing the laser threshold current value. .

The cladding layer is not limited to AlGaN ternary mixed crystal, but may be AlInGaN, AlGaNP, or AlGaN.
It may be a quaternary mixed crystal such as As. Further, the p-type cladding layer has a superlattice structure including a p-type AlGaN layer and a p-type GaN layer, or a p-type AlGa
It may have a superlattice structure including an N layer and a p-type InGaN layer.

In this embodiment, the crystal growth method using the MOCVD apparatus has been described as an example, but the molecular beam epitaxy method (MB
E) or hydride vapor phase epitaxy (HVPE) or the like may be used.

(Chip-forming step) The epi-wafer formed by the above-described crystal growth (wafer on which a nitride semiconductor multilayer film structure is epitaxially grown on a processed substrate) is subjected to MOCVD.
It is removed from the device and processed into a laser element. here,
The surface of the epitaxial wafer on which the nitride semiconductor multilayer film structure was formed had a depression, and was not completely and flatly buried.

Since the processed substrate 101 is an n-type conductive nitride semiconductor, an n-electrode 111 is formed on the back surface side in the order of Hf / Al (see FIG. 14). As the n-electrode, a stack of Ti / Al, Ti / Mo, or Hf / Au may be used. If Hf is used for the n electrode,
This is preferable because the contact resistance is reduced.

The p-electrode portion was etched in a stripe shape along the groove direction of the processing substrate 101, thereby forming a ridge stripe portion (see FIG. 1). In the case where the grooves of the processed substrate are square, any one of the <1-100> direction and the <11-20> direction of the nitride semiconductor may be selected as the longitudinal direction of the grooves. The ridge stripe portion had a stripe width W = 2.0 μm and was formed so as to be included in the above-described region I (see FIG. 1). Thereafter, a SiO ₂ dielectric film 113 is deposited, and the p-type GaN contact layer 11 is formed.
0 was exposed from the dielectric film, and a p-electrode 112 was formed thereon by vapor deposition as a Pd / Mo / Au laminate. Pd / Pt / Au, Pd /
A stack of Au or Ni / Au may be used. Further, a pad electrode made of Au may be interposed between the p electrode 112 and the wire bond.

Finally, the epi-wafer is cleaved at a plane perpendicular to the longitudinal direction of the ridge stripe, and a resonator length of 50
A 0 μm Fabry-Perot resonator was fabricated. The resonator length is generally preferably in the range of 300 μm to 1000 μm. The M-plane {1-100} of the nitride semiconductor crystal is an end face of a mirror end face having a cavity length in which a groove is formed along the <1-100> direction. The cleavage for forming the mirror end face and the division of the laser element
Was performed using a scriber from the back side of the. However,
Cleavage was not performed by scribing a scribe with a scriber across the entire back surface of the wafer, but was cleaved by scribing only a part of the wafer, for example, both ends of the wafer. As a result, the sharpness of the end face of the element and shavings due to scribe do not adhere to the epi surface, so that the element yield is improved. On the surface of the nitride semiconductor light emitting device (laser device) divided into chips,
There were two or more depressions sandwiching the ridge stripe portion of the nitride semiconductor light emitting device. The p-electrode 112 was formed on a region including two or more dents, and the wire bond was formed on a region including one or more dents.

The feedback method of the laser resonator is as follows.
Commonly known DFB (distributed feedback), DBR (distributed Bragg reflection) and the like can also be used.

After the mirror end face of the Fabry-Perot resonator is formed, dielectric films of SiO ₂ and TiO ₂ are alternately deposited on the mirror end face to form a dielectric multilayer reflective film having a reflectance of 70%. Been formed. As the dielectric multilayer reflective film, a multilayer film such as SiO ₂ / Al ₂ O ₃ can be used.

Although the n-electrode 111 was formed on the back surface of the processing substrate 101, a part of the n-type Al _0.05 Ga _0.95 N film 102 was exposed from the front side of the epi-wafer by using a dry etching method. An n-electrode may be formed on the region.

(Package mounting) The obtained semiconductor laser device is mounted on a package. When using a high output (30 mW or more) nitride semiconductor laser device, attention must be paid to heat dissipation measures. The high-power nitride semiconductor laser device can be connected to the package body with the semiconductor junction either up or down using In solder material, but it is preferable to connect with the semiconductor junction down, from the viewpoint of heat dissipation. . The high-power nitride semiconductor laser device can be usually directly attached to a package body or a heat sink portion. However, Si, AlN, diamond, Mo,
The connection may be made via a submount of CuW, BN, Fe, SiC, Cu, or Au.

As described above, the nitride semiconductor laser device according to the present embodiment is manufactured. Although the GaN processed substrate 101 is used in the present embodiment, another nitride semiconductor processed substrate may be used. For example, in the case of a nitride semiconductor laser, a layer having a lower refractive index than the cladding layer needs to be in contact with the outside of the cladding layer in order to make the vertical and transverse modes unimodal, and an AlGaN substrate can be preferably used. .

In the present embodiment, the formation of the nitride semiconductor laser element on the substrate having the depressions alleviates the crystal distortion and suppresses the occurrence of cracks.
A laser oscillation life of about 18000 hours was obtained with a laser output of 30 mW under the condition of an ambient temperature of 60 ° C., and an improvement in element yield by crack suppression effect was achieved.

Ninth Embodiment In the ninth embodiment, a nitride semiconductor light emitting diode (LED) element is formed on any one of the recessed substrates in the first to seventh embodiments.
At this time, the nitride semiconductor LED element layer was formed by a method similar to the conventional method.

In the nitride semiconductor LED device according to the present embodiment, the color unevenness is reduced and the light emission intensity is improved as compared with the conventional case. Particularly, an LED element having a short wavelength (450 nm or less) or a long wavelength (600 nm or more), such as a white nitride semiconductor LED element or an amber nitride semiconductor LED element using a nitride semiconductor as a raw material,
By being formed on the substrate with depressions in Embodiments 1 to 7, it was possible to have a light emission intensity about twice or more as compared with the related art.

[Embodiment 10] Embodiment 10 is different from Embodiment 8 and Embodiment 10 in that at least one of As, P, and Sb, which is to be substituted for a part of N, is included in the light-emitting layer. Same as 9. More specifically, at least one of the substitution elements of As, P, and Sb was included in the light emitting layer of the nitride semiconductor light emitting element by substituting at least a part of N of the well layer. At this time, when the composition ratio of the sum of As, P, and / or Sb contained in the well layer is x and the composition ratio of N is y, x is y
And x / (x + y) must be less than 0.3 (30%), preferably less than 0.2 (20%). Further, the lower limit of the preferable concentration of the total of As, P, and / or Sb was 1 × 10 ¹⁸ / cm ³ or more.

The reason is that the substitution element composition ratio x is 20%
If the composition ratio x is higher than 30%, the separation of the hexagonal system and the cubic system are mixed. This is because there is a high possibility that the crystallinity of the well layer will decrease when the process starts to shift to. On the other hand, if the total concentration of the substituting elements is less than 1 × 10 ¹⁸ / cm ³ , the effect of including the substituting element in the well layer becomes difficult to obtain.

The effect of the present embodiment is that the effective mass of electrons and holes in the well layer is reduced and the mobility is reduced by including at least one of As, P, and Sb in the well layer. growing. In the case of a semiconductor laser device, a small effective mass means that a carrier inversion distribution for laser oscillation can be obtained with a small current injection amount, and a large mobility means that electrons and holes disappear in the light emitting layer due to radiative recombination. This also means that new electrons and holes can be injected at high speed by diffusion. That is,
Compared to an InGaN-based nitride semiconductor laser device in which the light-emitting layer does not contain any of As, P, and Sb, in the present embodiment, the threshold current density is low and the self-sustained pulsation characteristics are excellent (the Excellent) semiconductor lasers can be obtained.

On the other hand, when the present embodiment is applied to a nitride semiconductor LED, As, P, and / or S
b, the conventional InGa
The In composition ratio in the well layer can be reduced as compared with the nitride semiconductor LED element including the N well layer. This means that a decrease in crystallinity due to the separation of the concentration of In can be suppressed. Therefore, the effect of the addition of the substitution element is synergistic with the effect of the nitride semiconductor LED according to the eighth embodiment, thereby further improving the emission intensity and reducing the color unevenness. In particular, a white nitride semiconductor LE using a nitride semiconductor as a raw material
As in the case of the D element and the amber nitride semiconductor LED element, the emission wavelength is short (450 nm or less) or long (600 nm).
nm or more), the well layer can be formed without a low or no In composition ratio, so that the color unevenness is small as compared with the conventional InGaN-based nitride semiconductor LED element, Strong emission intensity can be obtained.

[Eleventh Embodiment] In the eleventh embodiment, the nitride semiconductor laser device of the eighth or tenth embodiment is applied to an optical device. The blue-violet (380 to 420 nm wavelength) nitride semiconductor laser device according to the eighth or tenth embodiment can be preferably used in various optical devices. For example, when used in an optical pickup device, it is preferable in the following points. That is, such a nitride semiconductor laser device operates stably at a high output (30 mW) in a high-temperature atmosphere (60 ° C.), has few device defects, and has a long laser oscillation life. It is most suitable for an optical disk device for density recording / reproducing (the shorter the light wavelength, the higher density recording / reproducing is possible).

FIG. 14 is a schematic block diagram showing an optical disk device including an optical pickup such as a DVD device as an example in which the nitride semiconductor laser device according to the eighth or tenth embodiment is used in an optical device. I have. In this optical information recording / reproducing apparatus, a laser beam 3 emitted from a light source 1 including a nitride semiconductor laser element is modulated by an optical modulator 4 according to input information, and a scanning mirror 5 is provided.
And recorded on the disk 7 via the lens 6. The disk 7 is rotated by a motor 8. At the time of reproduction, the reflected laser light optically modulated by the bit arrangement on the disk 7 is detected by the detector 10 via the beam splitter 9, and thereby a reproduction signal is obtained. The operation of each of these elements is controlled by the control circuit 11. The output of the laser element 1 is usually 3 at the time of recording.
0 mW, and about 5 mW during reproduction.

The laser device according to the present invention can be used not only in the above-described optical disk recording / reproducing apparatus but also in a laser printer, a bar code reader, a projector using three primary colors of light (blue, green, and red) lasers. I can do it.

[Twelfth Embodiment] In the twelfth embodiment, the nitride semiconductor light emitting diode element according to the ninth or tenth embodiment is used in a semiconductor light emitting device. That is, the nitride semiconductor light emitting diode device according to the ninth or tenth embodiment has at least three primary colors of light (red, green,
For example, it can be used in (a semiconductor light emitting device) such as a display device. By utilizing such a nitride semiconductor light emitting diode element,
A display device with little color unevenness and high light emission intensity can be manufactured.

Further, such a nitride semiconductor light emitting diode element capable of producing three primary colors of light can be used in a white light source device. On the other hand, the nitride semiconductor light emitting diode device according to the present invention having an emission wavelength in the ultraviolet region to the violet region (about 380 to 420 nm) can be used as a white light source device by applying a fluorescent paint.

By using such a white light source, a backlight with low power consumption and high luminance can be realized instead of the halogen light source used in the conventional liquid crystal display. It can also be used as a backlight for a liquid crystal display of a man-machine interface in a mobile notebook computer or mobile phone,
A small and clear liquid crystal display can be provided.

[0164]

As described above, according to the present invention, in the nitride semiconductor light emitting device, the light emission lifetime and light emission intensity can be improved. Further, according to the present invention, in the nitride semiconductor light emitting device, it is possible to prevent cracks, electrode peeling, and wire bond peeling.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one example of a nitride semiconductor laser device formed on a substrate with a depression according to the present invention.

FIG. 2A is a schematic cross-sectional view showing an example of a processed substrate of a nitride semiconductor that can be used in the present invention;
(B) shows a processed substrate including a heterogeneous substrate.

FIG. 3 is a schematic cross-sectional view showing an example of a substrate having a depression that can be used in the present invention.

4A shows a crystal growth mode on a processed substrate according to the present invention, FIG. 4B shows a crystal growth mode when the processed substrate is completely and flatly covered with a nitride semiconductor multilayer film structure, (C) shows a crystal growth mode in selective growth using the crystal growth suppressing film.

FIG. 5 shows the shapes of grooves (concave portions) and hills (convex portions) formed on a processing substrate that can be used in the present invention;
(A) shows a case where grooves having two kinds of directions are orthogonal to each other, and (b) shows a case where grooves having two kinds of directions are 60
(C) shows the case where grooves having three directions cross each other at an angle of 60 °.

FIG. 6 is a diagram showing a relationship between a formation position of a ridge stripe portion of a nitride semiconductor laser device formed on a substrate having a depression which can be used in the present invention and a laser oscillation life.

FIG. 7 is a schematic cross-sectional view showing a preferable formation region of a light-emitting portion in a light-emitting element structure formed on a substrate with depressions that can be used in the present invention.

FIG. 8 is a schematic cross-sectional view showing another example of a substrate with a depression that can be used in the present invention.

FIG. 9 is a schematic cross-sectional view showing another example of a substrate with a depression that can be used in the present invention.

FIG. 10 is a schematic cross-sectional view showing another example of a recessed substrate that can be used in the present invention.

FIG. 11 is a schematic cross-sectional view showing another example of a recessed substrate that can be used in the present invention.

FIG. 12 is a schematic cross-sectional view showing another example of a substrate with a depression that can be used in the present invention.

FIG. 13 is a schematic cross-sectional view showing another example of a substrate with a depression that can be used in the present invention.

FIG. 14 is a schematic block diagram showing an example of an optical device including an optical pickup device using a nitride semiconductor laser device according to the present invention.

[Explanation of symbols]

100 substrate with depression, 101 processing substrate, 102 n
Type Al _0.05 Ga _0.95 N underlayer, 103 n type In _0.07 G
a _0.93 N anti-cracking layer, 104 n-type Al _{0. 1} Ga _0.9
N clad layer, 105 n-type GaN light guide layer, 106
Emitting layer, 107 p-type Al _0.2 Ga _0.8 N carrier block layer, 108 p-type GaN guide layer, 109 p-type A
l _0.1 Ga _0.9 N cladding layer, 110 p-type GaN contact layer, 111 n electrode, 112 p electrode, 113 S
iO ₂ dielectric film.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayuki Yuasa 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Shigetoshi Ito 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Mototaka Taniya 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5F041 AA14 AA31 CA34 FF01 FF16 5F045 AA04 AB14 AB17 AC08 AC12 AC19 AF04 AF09 AF12 BB13 CA09 DA52 DA53 DA55 DA60 5F073 AA13 AA45 AA51 AA55 BA05 CA07 CB02 CB05 CB07 CB22 DA05 EA26 EA29

Claims (25)

[Claims] 1. A processed substrate including a concave portion and a convex portion formed on a surface of a nitride semiconductor substrate or a surface of a nitride semiconductor layer grown on a substrate other than a nitride semiconductor, and grown on the uneven surface of the processed substrate. A light emitting element including a nitride semiconductor underlayer formed, and a light emitting layer including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between the n-type layer and the p-type layer on the nitride semiconductor underlayer. And a non-planarized recess above at least one of the concave portion and the convex portion even after growing the nitride semiconductor underlayer and the light emitting device structure. Object semiconductor light emitting device. 2. The nitride semiconductor light emitting device according to claim 1, wherein the entire processing substrate is made of a nitride semiconductor. 3. The nitride semiconductor light emitting device according to claim 1, wherein the concave portion is a stripe-shaped groove, and the convex portion is a stripe-shaped hill. 4. The uneven surface of the processed substrate is made of a nitride semiconductor, and a longitudinal direction of the groove and a longitudinal direction of the hill are substantially parallel to a <1-100> direction of the nitride semiconductor crystal. The nitride semiconductor light emitting device according to claim 3, wherein 5. The method according to claim 1, wherein the uneven surface of the processing substrate is made of a nitride semiconductor, and a longitudinal direction of the groove and a longitudinal direction of the hill are substantially parallel to a <11-20> direction of the nitride semiconductor crystal. The nitride semiconductor light emitting device according to claim 3, wherein 6. The light emitting device according to claim 6, wherein the depression does not exist above the width center of the groove, and the light emission of the light emitting element structure is at least 1 μm in the width direction from the groove width center and above a region within the width of the groove. The nitride semiconductor light-emitting device according to claim 3, wherein the nitride semiconductor light-emitting device includes a portion. 7. The dent is not present above the width center of the hill, and the light emitting element structure emits light above the region within the width of the hill at least 1 μm in the width direction from the width center of the hill. The nitride semiconductor light-emitting device according to claim 3, wherein the nitride semiconductor light-emitting device includes a portion. 8. The light emitting element structure, wherein the depression is formed above the groove, and is separated from a side end of the depression by 2 μm or more in a width direction of the groove and above a region within the width of the groove. The nitride semiconductor light-emitting device according to claim 3, wherein the light-emitting portion is included. 9. The dent is formed above the hill, and the light emitting device structure is located at least 2 μm in a width direction of the hill from a side end of the dent and above a region within the width of the hill. The nitride semiconductor light-emitting device according to claim 3, wherein the light-emitting portion is included. 10. The nitride semiconductor light emitting device according to claim 6, wherein said groove width is in a range of 4 to 30 μm. 11. The nitride semiconductor light emitting device according to claim 8, wherein said groove width is in a range of 7 to 100 μm. 12. The nitride semiconductor light emitting device according to claim 7, wherein the hill width is in a range of 4 to 30 μm. 13. The nitride semiconductor light emitting device according to claim 9, wherein the hill width is in a range of 7 to 100 μm. 14. The nitride semiconductor light emitting device according to claim 6, wherein the depth of the groove is in a range of 1 to 9 μm. 15. The groove has a depth of 1 μm or more,
And the remaining thickness between the bottom of the groove and the back surface of the substrate is 1
The nitride semiconductor light emitting device according to claim 8, wherein the thickness is at least 00 µm. 16. The nitride semiconductor underlayer is made of GaN.
, Si, O, Cl, S, C, Ge, Zn, Cd, M
at least one of g and Be impurity groups
Is contained in the GaN and the amount of addition is 1 ×
10¹⁷/ Cm ^Three5 × 10¹⁸/ Cm^ThreeMust be
The nitride semiconductor light emitting device according to claim 1, wherein: 17. The method according to claim 17, wherein the nitride semiconductor underlayer is Al _x Ga.
_1-xN (0.01 ≦ x ≦ 0.15) and Si,
O, Cl, S, C, Ge, Zn, Cd, Mg and Be
The Al _x Ga ₁ -xN contains at least one or more impurities in the impurity group of
^2. The nitride semiconductor light emitting device according to claim 1, wherein the nitride semiconductor light emitting device has a density of not less than ¹⁷ / cm ^{3 and not} more than 5 × 10 ¹⁸ / cm ³ . 18. The method according to claim 18, wherein the nitride semiconductor underlayer is In _x Ga.
_1-xN (0.01 ≦ x ≦ 0.15) and Si,
O, Cl, S, C, Ge, Zn, Cd, Mg and Be
And at least one type of impurity in the In _x Ga _1-x N is contained in the impurity group of
^2. The nitride semiconductor light emitting device according to claim 1, wherein the nitride semiconductor light emitting device has a density of ¹⁷ / cm ³ or more and 4 × 10 ¹⁸ / cm ³ or less. 19. The nitride semiconductor light emitting device according to claim 1, wherein an electrode is formed on a region including at least two of the depressions. 20. The nitride semiconductor light emitting device according to claim 1, wherein a dielectric film is formed on a region including at least two of the depressions. 21. The nitride semiconductor light emitting device according to claim 1, wherein one or more of the dents are included in a bonding region between a wire bond and the nitride semiconductor device. 22. The quantum well layer comprises As, P, and S
22. The nitride semiconductor light-emitting device according to claim 1, comprising at least one element of b. 23. An optical device comprising the nitride semiconductor light emitting device according to claim 1. Description: 24. A semiconductor light emitting device comprising the nitride semiconductor light emitting element according to claim 1. Description: 25. A processed substrate including a concave portion and a convex portion formed on a surface of a nitride semiconductor substrate or a surface of a nitride semiconductor layer grown on a substrate other than a nitride semiconductor is prepared. A light emitting element including a light emitting layer including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between the n-type layer and the p-type layer on the nitride semiconductor base layer A step of growing a structure, wherein even after growing the nitride semiconductor underlayer and the light emitting element structure, a non-planarized depression is formed above at least one of the concave part and the convex part. A method for manufacturing a nitride semiconductor light emitting device.